@gmaboof - so sorry to hear this! I can't speak to the leg pain but a rash is a known side effect, per leqvio.com. ("The most common side effects of LEQVIO were: injection site reaction [including pain, redness, and rash], joint pain, and chest cold.") Injection site reaction is experienced by 8% of patients. I would question the location, though, assuming you had the shot in the upper arm.
Since none of the topical creams (prescription and non prescription) I had on hand helped, my Derm prescribed Clobetasol Propionate .05% which did help the area heal a little faster. The rash was gone in about 1 month. Because the reaction after the 2nd shot was 2x as large, I'm bracing for my 3rd injection in July.
Have you checked this document available on the Leqvio website: https://www.novartis.com/us-en/sites/novartis_us/files/leqvio.pdf